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61f35cd2aa
It was recently discovered that the handling of CC values was actually broken
since overflow was not properly handled ('nsw' flag not checked for).
Add and sub instructions now have a new target specific instruction flag
named SystemZII::CCIfNoSignedWrap. It means that the CC result can be used
instead of a compare with 0, but only if the instruction has the 'nsw' flag
set.
This patch also adds the improvements of conversion to logical instructions
and the analyzing of add with immediates, to be able to eliminate more
compares.
Review: Ulrich Weigand
https://reviews.llvm.org/D66868
164 lines
2.7 KiB
LLVM
164 lines
2.7 KiB
LLVM
; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z14 | FileCheck %s
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;
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; Check that signed comparisons against 0 are only eliminated if the "nsw"
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; flag is present on the defining add (with register) instruction. For an
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; equality comparison, add logical can be used.
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define i32 @fun0(i32 %arg, i32 %arg2, i32 %arg3) {
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; CHECK-LABEL: fun0:
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; CHECK: jle .LBB0_2{{$}}
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; CHECK: je .LBB0_4{{$}}
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bb:
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%tmp2 = add nsw i32 %arg, %arg2
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%tmp3 = icmp sgt i32 %tmp2, 0
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br i1 %tmp3, label %bb3, label %bb1
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bb1:
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%tmp4 = add nsw i32 %arg, %arg3
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%tmp5 = icmp eq i32 %tmp4, 0
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br i1 %tmp5, label %bb4, label %bb2
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bb2:
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ret i32 0
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bb3:
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ret i32 1
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bb4:
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ret i32 2
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}
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; No "nsw" flag
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define i32 @fun1(i32 %arg, i32 %arg2, i32 %arg3) {
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; CHECK-LABEL: fun1:
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; CHECK: cijle
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; CHECK: alr
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; CHECK: jhe
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bb:
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%tmp2 = add i32 %arg, %arg2
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%tmp3 = icmp sgt i32 %tmp2, 0
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br i1 %tmp3, label %bb3, label %bb1
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bb1:
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%tmp4 = add i32 %arg, %arg3
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%tmp5 = icmp eq i32 %tmp4, 0
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br i1 %tmp5, label %bb4, label %bb2
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bb2:
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ret i32 0
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bb3:
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ret i32 1
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bb4:
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ret i32 2
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}
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; "nuw" flag
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define i32 @fun2(i32 %arg, i32 %arg2, i32 %arg3) {
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; CHECK-LABEL: fun2:
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; CHECK: cijle
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; CHECK: alr
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; CHECK: jhe
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bb:
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%tmp2 = add nuw i32 %arg, %arg2
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%tmp3 = icmp sgt i32 %tmp2, 0
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br i1 %tmp3, label %bb3, label %bb1
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bb1:
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%tmp4 = add nuw i32 %arg, %arg3
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%tmp5 = icmp eq i32 %tmp4, 0
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br i1 %tmp5, label %bb4, label %bb2
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bb2:
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ret i32 0
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bb3:
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ret i32 1
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bb4:
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ret i32 2
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}
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; Subtraction does not produce the value of zero in case of overflow, so
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; "nsw" is not needed for the equality check against zero.
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define i32 @fun3(i32 %arg, i32 %arg2, i32 %arg3) {
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; CHECK-LABEL: fun3:
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; CHECK: jle .LBB3_2{{$}}
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; CHECK: je .LBB3_4{{$}}
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bb:
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%tmp2 = sub nsw i32 %arg, %arg2
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%tmp3 = icmp sgt i32 %tmp2, 0
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br i1 %tmp3, label %bb3, label %bb1
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bb1:
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%tmp4 = sub nsw i32 %arg, %arg3
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%tmp5 = icmp eq i32 %tmp4, 0
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br i1 %tmp5, label %bb4, label %bb2
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bb2:
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ret i32 0
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bb3:
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ret i32 1
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bb4:
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ret i32 2
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}
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; No "nsw" flag
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define i32 @fun4(i32 %arg, i32 %arg2, i32 %arg3) {
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; CHECK-LABEL: fun4:
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; CHECK: cijle
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; CHECK: je .LBB4_4{{$}}
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bb:
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%tmp2 = sub i32 %arg, %arg2
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%tmp3 = icmp sgt i32 %tmp2, 0
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br i1 %tmp3, label %bb3, label %bb1
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bb1:
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%tmp4 = sub i32 %arg, %arg3
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%tmp5 = icmp eq i32 %tmp4, 0
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br i1 %tmp5, label %bb4, label %bb2
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bb2:
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ret i32 0
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bb3:
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ret i32 1
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bb4:
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ret i32 2
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}
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; "nuw" flag
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define i32 @fun5(i32 %arg, i32 %arg2, i32 %arg3) {
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; CHECK-LABEL: fun5:
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; CHECK: cijle
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; CHECK: je .LBB5_4{{$}}
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bb:
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%tmp2 = sub nuw i32 %arg, %arg2
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%tmp3 = icmp sgt i32 %tmp2, 0
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br i1 %tmp3, label %bb3, label %bb1
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bb1:
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%tmp4 = sub nuw i32 %arg, %arg3
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%tmp5 = icmp eq i32 %tmp4, 0
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br i1 %tmp5, label %bb4, label %bb2
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bb2:
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ret i32 0
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bb3:
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ret i32 1
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bb4:
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ret i32 2
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}
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